MechPilotH9/d9 fit: limit deviations and clearances (ISO 286)
Hole H9 with shaft d9, hole-basis system. Limit deviations and the resulting clearances for nominal sizes up to 500 mm, in micrometres. Clearance fit at every size step below.
| Nominal size (mm) | Hole H9 (µm) | Shaft d9 (µm) | Clearance (µm) | Fit | ||||
|---|---|---|---|---|---|---|---|---|
| over | up to | ES | EI | es | ei | max. | min. | |
| 0 | 3 | +25 | 0 | −20 | −45 | +70 | +20 | Clearance |
| 3 | 6 | +30 | 0 | −30 | −60 | +90 | +30 | Clearance |
| 6 | 10 | +36 | 0 | −40 | −76 | +112 | +40 | Clearance |
| 10 | 18 | +43 | 0 | −50 | −93 | +136 | +50 | Clearance |
| 18 | 30 | +52 | 0 | −65 | −117 | +169 | +65 | Clearance |
| 30 | 50 | +62 | 0 | −80 | −142 | +204 | +80 | Clearance |
| 50 | 80 | +74 | 0 | −100 | −174 | +248 | +100 | Clearance |
| 80 | 120 | +87 | 0 | −120 | −207 | +294 | +120 | Clearance |
| 120 | 180 | +100 | 0 | −145 | −245 | +345 | +145 | Clearance |
| 180 | 250 | +115 | 0 | −170 | −285 | +400 | +170 | Clearance |
| 250 | 315 | +130 | 0 | −190 | −320 | +450 | +190 | Clearance |
| 315 | 400 | +140 | 0 | −210 | −350 | +490 | +210 | Clearance |
| 400 | 500 | +155 | 0 | −230 | −385 | +540 | +230 | Clearance |
Max. clearance = ES − ei, min. clearance = EI − es; a negative clearance is an interference. Above 500 mm MechPilot’s data holds no fundamental deviations, so no values are shown.
Example: ⌀25 H9/d9
- Hole ⌀25 H9: 25.000 to 25.052 mm
- Shaft ⌀25 d9: 24.883 to 24.935 mm
How the values are computed
Each deviation comes from the standard tolerance grade (IT) of the class and its fundamental deviation for the size step, combined by these rules of ISO 286-1:
- Holes A to H: the fundamental deviation is the lower deviation EI (positive or zero); ES = EI + IT. ISO 286-1:1988, 9.2 and Figure 18.
- Shafts a to h: the fundamental deviation is the upper deviation es (negative or zero); ei = es - IT. ISO 286-1:1988, 9.1 and Figure 17.
ISO fits explained · ISO 286 standard tolerance grades IT01 to IT18
Other fits
H11/c11 H8/f7 H7/g6 H7/h6 H7/js6 H7/k6 H7/n6 H7/p6 H7/s6 H7/u6
Source and verification
- Standard
- ISO 286-1:2010 Geometrical product specifications (GPS) - ISO code system for tolerances on linear sizes - Part 1: Basis of tolerances, deviations and fits; ISO 286-2:2010 Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts
- Verification
primary(the standard’s own text was seen)- Verified from
- https://cdn.standards.iteh.ai/samples/54915/7d6147c29fed4e31af36b60561e88752/ISO-286-2-2010.pdf (ISO 286-2:2010 preview: Table 1; Tables 2 and 3 for holes A to E)
- https://law.resource.org/pub/in/bis/S01/is.919.1.1993.pdf (IS 919 (Part 1):1993, identical with ISO 286-1:1988: clause 9, Tables 2 and 3, Annex A)
- https://cdn.standards.iteh.ai/samples/45975/c0a5df14167f48eebc6c17dc4da5f9c4/ISO-286-1-2010.pdf (ISO 286-1:2010 preview: terms and definitions only, no tables)
- Verification notes
- itGrades: ISO 286-2:2010 Table 1 (reproduced there from ISO 286-1:2010), read from the standard's own preview on 2026-10-22. IT01 and IT0 are not given above 500 mm (null).
- fundamentalDeviations: read from ISO 286-1:1988 Tables 2 (shafts) and 3 (holes) in the identical Indian adoption IS 919 (Part 1):1993. The 2010 edition's Tables 2 and 3 were not seen. Holes A, B, C, D and E were cross-checked against ISO 286-2:2010 Tables 2 and 3 (lower limit deviations EI) and agree for every size step up to 500 mm. The other letters come from the 1988 edition only (see docs/to-verify.md).
- The Delta values equal IT(n) - IT(n-1) of itGrades for every step above 3 mm; scripts/check-library.mjs checks this.
- Tolerance grades
- ISO 286-2:2010, Table 1 "Values of standard tolerance grades for nominal sizes up to 3 150 mm" (from ISO 286-1:2010, Table 1). Converted to mm; one value per entry of sizeSteps (main-step values repeated over their intermediate steps).
- Fundamental deviations
- ISO 286-1:1988, Table 2 (shafts: upper deviation es for a to h, lower deviation ei for k to zc) and Table 3 (holes: lower deviation EI for A to H, upper deviation ES for K to ZC), in mm with sign. Arrays follow sizeSteps; null = blank in the table, or not stored (every value above 500 mm is left out here).
- Data file
library/fits/iso-286.json
Values that could not be checked against the standard are left out and listed in docs/to-verify.md. Check the standard itself before you rely on a value for production, and report any mistake on GitHub. to-verify.md · Issues